1. Technical Field
The present invention is generally directed to a data verification system for use in a computer system such as an embedded controller, or the like. More particularly, the invention is directed to a system that may quickly verify data integrity using multiple data verification operations, where the data verification operations may have differing computational costs.
2. Related Art
Computers, embedded controllers, and other microprocessor based devices typically employ one or more memory storage units that are used for the reading and writing of data used in the overall system. The memory storage may take on a variety of different forms including, but not limited to, hard disk drives, floppy disk drives, integrated circuit memory, etc.
In each device, some manner of controlling the reading and writing of data to and from the memory storage units is often necessary. To this end, each device may include an operating system that acts as an interface between the high-level application programs executed by the processor and the system hardware, such as the memory storage units. File system software may be included in the operating system, or it may be provided as an ancillary software component that interacts with the operating system. In either instance, the file system software may be used to organize the data within the memory storage units for ready access by the processor.
Data verification software also may be provided for checking and/or maintaining the integrity of the data within the file system. In many systems, the data verification software verifies the integrity of the data each time it is read from the memory storage unit(s) as well as each time it is stored on the memory storage unit(s). The data verification software may use a single data verification method, such as an Error Correcting Code (ECC) method, during each verification. In accordance with this method, a coding function known as the ECC coding function is used to generate an ECC code in connection with the data as it is stored during a write operation. The generated ECC code is stored along with the data for subsequent verification during a read operation. During a read operation, the ECC coding function is again applied to the data and the newly generated ECC code is compared to the ECC code stored with the data during the prior write operation. If the ECC codes differ from one another, the data has been corrupted. Depending on the degree of corruption, either or both of the ECC codes may be used to correct the errors in the data.
While ECC techniques are effective for correcting single bit errors or double bit errors, they can be computationally expensive to implement, particularly when the ECC code generation takes place during every read and write operation. The integrity of the entire data of the file system also may be verified during system start up, leading to substantially delayed boot times when ECC techniques are employed. This problem is further exacerbated when more sophisticated coding functions allowing for correction of multi-bit errors are employed. Accordingly, an alternative to the existing data integrity verification operations is needed.